SSL certificate problem: unable to get local issuer certificate

Hi ,Iam trying to create a centos7.1 box using test kitchen,But iam getting ssl certificate issue.I given proxy URL in kitchen.yml file.

Error Logs:

-----> Starting Kitchen (v1.10.2)
-----> Creating …
/opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/mixlib-shellout-2.2.6/lib/mixlib/shellout/unix.rb:338: warning: Insecure world writable dir /usr/local/bin in PATH, mode 040777
Bringing machine ‘default’ up with ‘virtualbox’ provider…
==> default: Box ‘bento/centos-7.2’ could not be found. Attempting to find and install…
default: Box Provider: virtualbox
default: Box Version: >= 0
==> default: Loading metadata for box 'bento/centos-7.2’
default: URL:
==> default: Adding box ‘bento/centos-7.2’ (v2.3.0) for provider: virtualbox
default: Downloading:
An error occurred while downloading the remote file. The error
message, if any, is reproduced below. Please fix this error and try

   SSL certificate problem: unable to get local issuer certificate
   More details here:

   curl performs SSL certificate verification by default, using a "bundle"
    of Certificate Authority (CA) public keys (CA certs). If the default
    bundle file isn't adequate, you can specify an alternate file
    using the --cacert option.
   If this HTTPS server uses a certificate signed by a CA represented in
    the bundle, the certificate verification probably failed due to a
    problem with the certificate (it might be expired, or the name might
    not match the domain name in the URL).
   If you'd like to turn off curl's verification of the certificate, use
    the -k (or --insecure) option.